| [ Summary ] |
The kidneys are considered a critical organ in relation to cadmium (Cd) toxicity because the metal accumulates in the proximal tubule where it produces its earliest and most prominent toxic effect. This paper reviews the epidemiology, pathophysiology, clinical course, prognosis, and screening of Cd-nephropathy observed in the local inhabitants of the Cd-polluted Jinzu River basin in Toyama Prefecture, Japan. Although a marked decline in Cd levels in rice has been achieved due to the replacement of polluted paddy field soil, Cd-nephropathy is still prevalent and is a progressive, and irreversible condition in the older local population. A 27-year follow-up study revealed that in severe cases of Cd-nephropathy with urinary excretion of β2-microglobulin (Uβ2-MG) higher than 10 mg/gCr, decreased renal tubular reabsorption of phosphates and decreased glomerular filtration rates were evident. Therefore, continued screening and long-term monitoring of renal tubular functions as well as bone metabolism are essential for the inhabitants of this area. Large measured changes in urinary excretion of Uβ2-MG provide a very sensitive monitoring technique ; in spite of the drawback that β2-MG is unstable in acidic urine. The magnitude of Uβ2-MG is useful to grade the severity of Cd-nephropathy. |